Herd immunity

[jumstead1023]

Please explain in layman’s terms.

 

[Dr. Sara]

Suppose that most individuals of a group have been exposed to something (a pathogen, such as a virus), and developed immunity (resistance) to it.
Now, even if a few members of the group are not immune to this pathogen, they are still unlikely to encounter it, or become ill from it, because most members of the group are immune to it, and won't have it or spread it.
This is herd immunity.
HOWEVER, nothing is ever that simple, right? For instance:
If immunity to the pathogen is not strong, or immunity decreases, individuals may become ill or carry the pathogen.
If the pathogen changes, previously immune individuals may no longer be immune.
If the population is not closed, and new individuals enter it, the situation changes depending on their state of immunity.
I hope this helps!
Dr. Sara

 

[jumstead1023]

Suppose that most individuals of a group have been exposed to something (a pathogen, such as a virus), and developed immunity (resistance) to it.
Now, even if a few members of the group are not immune to this pathogen, they are still unlikely to encounter it, or become ill from it, because most members of the group are immune to it, and won't have it or spread it.
This is herd immunity.
HOWEVER, nothing is ever that simple, right? For instance:
If immunity to the pathogen is not strong, or immunity decreases, individuals may become ill or carry the pathogen.
If the pathogen changes, previously immune individuals may no longer be immune.
If the population is not closed, and new individuals enter it, the situation changes depending on their state of immunity.
I hope this helps!
Dr. Sara

Thank you